Research is being conducted to elucidate the roles of pyoverdin, pyocyanin, and pyochelin in infections caused by P. aeruginosa. Pyochelin and pyoverdin appear to be siderophores for iron transport. The structure of pyochelin is being determined by mass spectroscopy and NMR spectroscopy. The structure of pyoverdin is being determined by mass spectroscopy of hydrolysis products. There is no growth promoting effect of pyocyanin for P. aeruginosa and the function of this pigment remains obscure. Since pyocyanin synthesis is late during the growth phase, experiments are being conducted to determine the effects of pyocyanin on bacterial longevity. NMR and EPR spectroscopy are being used to determine the configuration of pyocyanin in the oxidized and reduced states. A model for the study of virulence of P. aeruginosa in thoracic and peritoneal infections has been developed and these pigments will be used in this study to determine the effects upon the outcomes of the infections.